:root {
    --primary-blue: #6c8cff;
    --primary-purple: #a68fff;
    --max-width: 1440px;
    --content-padding: clamp(20px, 5vw, 50px);
    --section-spacing: clamp(30px, 5vw, 50px);
    --card-gap: clamp(20px, 3vw, 30px);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    margin: 0;
    padding: 0;
    min-height: 100vh;
    font-family: 'Segoe UI', Arial, sans-serif;
    line-height: 1.6;
    background: #f5f7fa;
    background-size: 400% 400%;
    animation: gradientBG 15s ease infinite;
}

@keyframes gradientBG {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

h1 {
    text-align: center;
    font-size: clamp(28px, 4vw, 36px);
    color: #2c3e50;
    margin-top: 110px;
    margin-bottom: 40px;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 var(--content-padding);
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: var(--card-gap);
}

.card {
    background: white;
    border-radius: 15px;
    padding: clamp(20px, 4vw, 30px);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    margin-bottom: var(--card-gap);
}

.card h2 {
    font-size: clamp(20px, 2.5vw, 24px);
    color: #2c3e50;
    margin-bottom: 20px;
    border-bottom: 2px solid #e6e9ec;
    padding-bottom: 10px;
}

.feature-item {
    margin-bottom: 25px;
    padding: 15px;
    border-radius: 8px;
    background: #f8f9fa;
    transition: transform 0.3s ease;
}

.feature-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.feature-title {
    font-size: clamp(16px, 2vw, 18px);
    color: #3498db;
    margin: 10px 0;
    font-weight: 600;
}

.feature-desc {
    font-size: clamp(14px, 1.6vw, 16px);
    color: #666;
    line-height: 1.6;
}

/* 响应式布局 */
@media (max-width: 768px) {
    .container {
        grid-template-columns: 1fr;
        padding: 15px;
    }
    
    .card {
        padding: 20px;
        margin-bottom: 20px;
    }
    
    .feature-item {
        padding: 12px;
    }
}

@media (min-width: 769px) and (max-width: 1024px) {
    .container {
        grid-template-columns: repeat(2, 1fr);
        gap: 20px;
        padding: 20px;
    }
}

@media (min-width: 1025px) {
    .container {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* 手机端 */
@media (max-width: 576px) {
  .box { width: 100%; }
}

/* 平板 */
@media (min-width: 577px) and (max-width: 992px) {
  .box { width: 50%; }
}

/* 桌面端 */
@media (min-width: 993px) {
  .box { width: 25%; }
}